Induction-motor-control system



July l, 1930. H. D.v ELSE 1,768,897

` INDUCTION MOTOR CONTROL SYSTEI Filed Sept. l1, 1929 `Illlllllllllll INVENTOR Harry D.E1se

' ATTORNEY,

vate-'eased UNITED sine'ras PATENT OFFICE HARRY D. ELSE, OP SPRINGFIELD, MASSACHUSETTS, ASSIGNOB T0 WESTINGHOUSE ELECTRIC & MANUFACTURING CQMPANY, A CORPORATION OP PENNSYLVANIA .INDUUIION-MOTOEGONTBOL SYBTEI Application led September 1l, 1989. lerlll lo. 891,786.

My invention relates to alternating-current motors and, more particularly, to repulsioninduction motors.

An object of my invention is toprovide a relatively ysimple means for ermitting the starting of a repulsion-induction motor and of effectively protecting the same against excessive over oads.

In practicing my invention, I provide, in combination with a repulsion-induction motor having a stator-energizing winding, a rotor core, a rotor winding and ay commutator cylinder, a centrifugally-actuable commutator-shortcircuiting device and brushes, and an electro-magnetic switch, includin' a movable core member, an actuating coil or moving the core member and the switch to its open position and manually actuable means for closing or for opening the switch.

The single figure of the drawing shows a motor of the repulsion-induction typepartially in side elevation 'and partiall in section to show the inner parts thereo and an electro-magnetic switch comprising my invention also partially in side elevation and partially in section.

A repulsion-induction motor 11 comprises the usual housing 12, a laminated stator 13 and a stator energizing windin 14. A rotor shaft 16 has the usual laminate rotor core 17 and a rotor winding 18 mounted thereon. A commutator cylinder, comprising a hub 19 and'segments 21, is also provided, the segments being electrically-connected to the terminals of the several coils 18, all in a manner well known in theart.

A centrifugally actuable commutatorshort-circuiting device 22 is provided and, while a specific construction thereof is shown in the drawings as embodying an annular member 23 mounted on the shaft, a plurality of weight members 24Y pivotally mounted thereon and a garter springr 26 for yieldingly holding th weight members in positions to be disengaged from the front or end faces of the commutator segments 21, I do not desire to be limited thereto. as any eective shortcircuitng device may be employed.

A plurality of brushes 27 and brushholders 23 are supported by an end bracket 29 of the motor and insulated therefrom by bushings -While I have illustrated and described a specific embodiment of motor structure, commutator, commutator short circuiting device, brushholders and brushholder mountings, these have been shown and described for illustrative purposes only and any structures equivalent to those shown in the drawings msinbe employed.

electro-magnetically actuated switch, designated generally by the numeral 33, may comprise a skeleton frame member 34 of substantially rectangular sha e. A block 36 of electric insulating materia may be located at the bottom portion of the frame 34 and have mounted thereon, in any` suitable manner, contact members 37 and 38.

A cooperating contact bridging member 39 is insulatedly mounted on a movable magnetizable core member 41 and particularly at the lower end thereof. Each of the guide rods 42 and 43 may have one end fixedly mounted in the Ipper part of the frame 34 and may extend ownwardly therefrom and into suitable longitudinally extending openin 44 in the core member 41.

t is desired that the bridging member 39 shall have two limiting positions only and that it shall move from the one to the other of these positions with a snap action, and, for this purpose, two resilient arms 46 and 47 are provided which extend between the lower portion of the core member 41 and the inside surfaces of the vertically extending portions of the frame 34, in substantially the manner and location shown in the drawing. The arms 46 and 47 constitute a toggle and will maintain the bridging member 39 and the core 41 in either one of their limiting posig tions in which the bridging member 39 yis in engagement with the contact members 37 and 38 or is disengaged therefrom.

A coil 48 is provided for actuating the core member 41 in such direction as to cause open ing movement of the switch, the coil being suitably so supported within the frame 34 as to be fixed relatively thereto.

Manually actuable means for moving the core member 41 and the bridging member 39 may include a lever 51 pivotally mounted on an extension 52 of the frame 34, a knob 53 and a rod 54 pivotally mounted at one end of' the lever 51, the lower end of the rod 54 being secured to the core member 41. A second knob 56 is mounted in the otherI end of the lever 51. Pressure on the knob 53 causes movement of the core 41 and the bridginw member 39 to close the circuit controlled thereby, and pressure on the knob 56 causes movement of the core and bridging member in the other direction to open the switch.

The contact member 37 is connected, by a conductor 5T. to one terminal of the statorenergizing winding 14, while the other terminal thereof is connected to a supply-circuit conductor 58. A second supply-circuit conductor 59 is electrically connected to contact member 38.

The terminals of coil Lt8 are so connected, by conductors 61 and 62, to the brushholders 28 ot' respectively opposite polarities that the .coil 48 may be energized by the electro-motive forces generated in the rotor winding 18 so long as the commutator and the rotor winding are not short circuited by the shortcircuiting device 22.

The operation of the device and erstem embodying my invention may be briefly de-v scribed follows: As is well known, a repulsion-induction motor will start as a repulsion motor when the circuit through the stator-energizing winding is closed by means of a suitable switch. At starting and up to a predetermined speed, the siort-circuiting device QQ will be out of engagement with the commutator. An operator, pressing on the knob 53, will close the circuit with a snap action and will maintain the pressure required to hold the switch closed against the decreasing pull of the coil 48 as it is energized from the rotorwinding 18 in accordance with the increasing speed of the rotor. At a predetermined speed. the centrifugally actu able short-circuiting means is operated to short circuit the winding and, therefore, no current will traverse the coil 48. `When the motor comes up to its normal operatingr speed, pressure on the knob 53 may be. released.

The motor will now operate at speeds in accordance with the load and the design constants of the motor. It extreme overload conditions occur which so reduce the speed ot the motor as to cause ii' to drop out ot step which, as is well known, will occur atti. the maximum pull-out torque is exceeded, the commutator short-circuitiug device will he operated to remove the short circuit from the commutator and rotor winding, the coil t8 will be energized and will cause movement of the core 41 whereby the switch controllin the stator-energizing winding is opened and the stator winding is deenergized to shutdown ofthe motor.

In case the line circuit of the motor is momentarily deenergized after the motor has been operating, the switch 33 will initially remain in its closed position. As soon as the line is again energized, the initial rush of current through the motor-energizing winding (assuming the rotor to be stat1onary) will be relatively large and will efect opening of the switch, thereby preventing re-operation of the motor. Such an operating feature is very desirablel on manually operable switches used tor this purpose.

lf an operator should desire to manually operate the switch to open the circuit, he need only press on the knob 56,' and the toggle jointmembers will insure quick and complete opening of the control switch.

Various modifications may be made in the device and system embodying my invention without departing from the s irit and scope thereof, and I desire, there ore, that only such limitations shall be placed thereon as are imposed by the prior art or are set fort-h in the appended claims.

I claim as my invent-ion:

1. A control system for a repulsion-induction motor having a stator-energizing winding, a rotor, a rotor winding, a commutator cylinder and brushes, and a centrifugallyactuable commutator-sliort-circuiting device, said system including an electromagnetic switch for the stator-energizing Winding, means for connecting the coil of said switch to said brushes and manually-actuable means for closing said switch.

2. A control system for a repulsion-induction motor having a statorenergizing Winding, a rotor, a rotor Winding, a commutator cylinder and brushes, and a centrifugallyactuable commutator-short-circuiting device, said system including a switch for the statorenergizing winding, a. movable magnetizable core member for the switch, an actuating coil for the core, means for connecting the coil to the brushes, resilient means for yieldingly holding the core and switch in either one of two limiting positions and manually-actuable means for closing said switch.

3. A control system for a repulsioninduction motor having a stator-energizing winding, a rotor, rotor winding, a commutator cylinder and brushes, and a centrifugallyactuable cominutator-sliort-circuiting device. said system including a switch for the suite,ry winding, a magnetizable core member for the teh, a coil for moving the core to effect g- .t the switch, n. for electrical t-i'mnecting the coil to the brushes to be enegized by the rotor winding under predetermined operating conditions and manually actuable means4 for moving said core to close said switch.

4. A control system for a repulsioninduction motor having a stator-energizing wind- 5 ing, a rotor, a rotor Winding, a commutator cylinder and brushes, and a centrifugallyactuable commutetor-short-circuitin device, said system including a switch for t e stator winding, a magnetizable core for the switch, lo means operatively associated with said core and switch to cause movement thereof to be effected with a snap action a coil for moving l the core to effect opening oi the-switch, means for connecting the coil to the brushes to be energizedby the rotor winding under predetermined operating conditions and manually-operable means for moving the core to close and to open said switch. Y

5. Means for deenergizing a repulsion-induction motor having a stator-energizing winding, a rotor, a rotor winding, a commutator cylinder, brushes and a centrifugallyaetuable commutator-short-circuiting device, said means including an electromagnetic switch having an actuatin coil and means for electrically connecting 1t to the brushes, said coil being effective to cause Aopening movement of the switch u on disengagement of the centrifugally-actua le shortfcircuiting so device from the commutator.

In testimony whereof, I have hereunto subscribed my name this 27th day of August,

HARRY D. ELSE. 

